Simulation results were presented concerning the structural and the diffusive properties of small (3 to 7 atom) 2D Au clusters on the Cu(111) surface (table 13). It was found that in the normal to the surface direction the clusters were expanded, while the surface layer was contracted, depending on the cluster size, these relaxations exhibiting power law temperature dependence. The mean-square displacements of both cluster and surface atoms increased linearly with temperature, while size dependence was found for the cluster atoms. Furthermore, the trajectory analysis revealed a lot of cluster diffusion processes among which concerted motion events, in agreement with available theoretical and experimental data. However, it comes out that the diffusion takes place mainly via mechanisms consisted of a rapid succession of sub-processes, each involving few cluster atoms. Moreover, the total atomic and cluster diffusion coefficients were calculated and it was found that they exhibited Arrhenius behaviour, from which were deduced the corresponding activation energies.

Structural and Diffusive Properties of Small 2D Au Clusters on the Cu(111) Surface. Papathanakos, V., Evangelakis G.A.: Surface Science, 2002, 499[2-3], 229-43

Table 13

Diffusion parameters for Au clusters on Cu(111)